Well casing releasing coupling



May 5, 1964 F. E. CHANCELLOR ETAL WELL CASING RELEASING COUPLING 2 Sheets-Sheet 1 Filed April 24, 1962 INVENTORJ'. fimssr 45 5%41/654404 J? 0/4 May 5, 1964 F. E. CHANCELLOR ETAL 3,131,765

WELL CASING RELEASING COUPLING Filed April 24, 1962 2 Sheets-Sheet 2 NVENTORS'. HANCELLOQ, Gavan .404;

a wr v 2 IA\ United States Patent This invention relates to the art of completing oil wells to prepare these for production from a plurality of oil bearing horizons and particularly to a novel releasing coupling for accomplishing a controlled separation of the casing between successive cementing operations.

The present invention is an improvement upon the releasing coupling disclosed in our copending application for patent Serial No. 48,933, filed August 11, 1960. While entirely satisfactory in cementing operations not requiring rotation of the casing, the releasing coupling shown iri said application was not especially adapted for jobs where the casing had to be rotated.

It is an object of the present invention to provide a releasing coupling which is equally adapted for use in cementing jobs whether or not rotation of the casing is required during the job.

[mother object is to provide such a releasing coupling including an axial lock having an exceptionally high lifting capacity.

A further object of the invention is to provide such a lock which is readily subject to release by a plug preceding a charge of cement being pumped down the casing.

Still another object of the invention is to provide such a releasing coupling, a plurality of which may be inserted in the casing at different levels and selectively actuated to facilitate cementing off water zones at three or more horizons in the well.

The manner of accomplishing the foregoia objects as well as further objects and advantages will be made manifest in the following description taken in connection with the accompanying drawings in which FIG. 1 is a diagrammatic vertical sectional view of an open well bore illustrating an initial cementing operation cementing off a lower water zone in said bore the cementing operation being conducted through a casing, upper and lower sections of which are jo ned together by a preferred embodiment of the releasing coupling of the invention.

FIG. 2 is a diagrammatic vertical sectional view similar to FIG. 1 illustrating the completion of a double cementing operation in said well bore which was accomplished by the separation of the upper and lower sections of the well casing by separating the upper and lower members of the releasing coupling of the invention. This view also shows the introduction of a perforated lower section of a striu of pump tubing for producing oil from two spaced horizons in said bore.

FIG. 3 is a horizontal sectional view taken on line 3-3 of HG. 6 and illustrating two lugs provided to extend radially from the male sleeve of the coupling into circumferential passages in the female sleeve so as to positively prevent further extension of the male sleeve into the female sleeve and thus maintain these sleeves in interlocked relation with each other.

FIG. 4 is a view similar to FIG. 3, is taken on line 44 of FIG. 8 and illustrates the positions of the aforesaid lugs following a slight clockwise rotation of the male sleeve of the coupling from the position in which this is shown in FIG. 3 and which brings said lugs into axial alignment with the axial passages provided therefor in the female sleeve.

FIG. 5 is a diagrammatic perspective view of the block mounting spider and rubber diaphragm associated therewith which is provided for selective actuation by a cement "'ice plug travelling down the casing with the circulating fluid.

FIG. 6 is a fragmentary vertical sectional view through a preferred embodiment of the coupling of the invention and is taken on line 66 of FIG. 3. This View shows the coupling as introduced into the well with the male lugs engaging shoulders on the female sleeve so as to positively prevent unlocking of the locking means on the coupling even though the plug actuated tripping means had been actuated.

FIG. 7 is a view similar to FIG. 6 and illustrates engagement of the block withdrawing diaphragm by a cement plug too large to pass through the axial hole provided in said diaphragm whereby pressure of the circulating liquid in the casing is applied to the diaphragm so as to force this downwardly and withdraw said blocks from their positions in which they withhold the male sleeve of the coupling from further penetration of the female sleeve thereof. Attention is drawn to the fact that the lugs on the male sleeve are still located in the circumferential passages formed in the female sleeve so in spite of the removal of the blocks from between the extremity of the male sleeve and the annular shoulder provided internally on the female sleeve, the coupling still remains in a locked condition.

FIG. 8 is a view similar to FIG. 7 showing the male member of the coupling rotated, as by rotation of the upper section of the casing secured thereto, to bring the lugs provided on the male sleeve into the axial passages provided in the female sleeve so as to permit the male sleeve to fully penetrate the female sleeve and bring the extremity of the male sleeve against the internal annular shoulder formed on the female sleeve at the juncture thereof with the female coupling member. It is also to be noted that the balls formerly locking the two coupling members against axial separation have now dropped down into the annular ball escape channel formed in the inner surface of the female sleeve so as to leave the two coupling members free for axial separation whenever the upper section of the casing is lifted.

FIG. 9 is a view similar to FIG. 8 showing the lifting of the upper coupling member on which the male sleeve is formed thus completely separating the coupling.

FIG. 10 is a fragmentary enlarged detail view taken on the line li?1tl of FIG. 6 and illustrating the two ball races employed in the locking means with the ball bearing balls of said means occupying said two races and thus locking the upper and lower coupling members from axial separation.

FIG. 11 is a View similar to FlG. l0 and is taken on the line lil1 of PEG. 8 to illustrate the gravitation of the ball bearing balls from the locking means immediately following the full penetration of the female sleeve by the male sleeve of the coupling.

Referring specifically to the drawings, an open well bore 15 is shown in FIG. 1 as penetrating through a water zone 16, an oil Zone 17, a water zone 18 and terminating at a lower oil zone 19. These zones are separated by dry formation barriers 2%, 21, 22 and 23. The bore 15 terrm'nates as it enters the oil zone 19 and has a short pilot bore 24 extending axially downwardly therefrom. A string of cashig 25 is also shown in bore 15 this casing including an upper casing section 26 and a lower casing section 27, these two being connected together by a releasing coupling 28 which comprises a preferred embodirnent of the present invention. The lower end of easing section 27 is provided with a bull nose 39 having a central aperture through which circulating liquid may be discharged downwardly.

With the casing 25 thus positioned, a charge of cement 31 has been pumped downwardly with a circulating fluid through the casing 25 and out through the bull nose 3%) so as to occupy the space in the bore 15 surrounding the casing section 27 and allowed to set so as to immobilize this casing section and seal the water Zone 18 from the balance of the bore.

FIG. 2 illustrates the completion of the cementing job started in FIG. 1, this having been effected by separating the upper and lower portions of the releasing coupling 28, lifting the upper casing section 26 to the position in which it is shown in FIG. 2 and then pumping a charge of cement 32 downwardly and out at the lower end of the casing section 26 so that this cement flows upwardly around this casing Section and cements the same in place and seals off water zone 16 from the balance of the bore 15. When the charges of cement 31 and 32 have adequately set, the cement and other debris remaining within the casing sections 26 and 27 are bored out and the well bore itself deepened as shown at 33 and a perforated oil production tubing 34 is thereupon installed in the well.

The primary function of the present invention having been thus explained the preferred embodiment of the invention illustrated herein will now be specifically described.

It is first desired to emphasize the very close space limits within which the coupling 28 is confined. The coupling 28 includes two tubular members one a male member 35 and the other a female member 36 which are preferably formed of steel and both have an internal diameter which is that of the casing and an external diameter which is that of standard threaded couplings used in connecting adjacent sections of such casing. Being diagrammatic in character, FIGS. 1 and 2 omit the showing of such standard couplings in the casing 25. It is nonetheless evident that the coupling 28 possesses a great advantage in that it will pass through any opening which a standard coupling will pass through and moreover it will allow any tool to pass through the coupling which will be admitted into the casing itself.

The male coupling member has an internally threaded receptacle 37 formed at its upper end which threadedly receives the adjacent end of the upper casing section 26. The female coupling member 36 has an externally threaded nipple 38 provided on its lower end which screws into a standard coupling 39 on the upper end of the lower casing section 27.

Male coupling member 35 has an intermediate portion formed by turning down the outer diameter of the member 35 to form a cylindrical outer surface 46 of reduced diameter in which is provided an annular groove 47 for receiving an O-ring 48. Below the portion 45, the external surface of the male coupling member 35 is further turned down to provide an external cylindrical surface 49 and provide a male sleeve 50 integral with the male member portion 45. A portion of the operation of reducing the external diameter of the member 35 in producing the male sleeve 50 is done with a milling machine to leave a pair of diametrically opposed rectangular lugs 51 and 52 extending radially from the surface 49 at points close to the male member portion 45. Turned in the surface 49 is an annular ball bearing ball race 53 the upper wall 54 of which is radial and the lower wall 55 of which is beveled (FIG. 11).

The female coupling member 36 has its interior recessed by a relatively long counterbore in which are formed an annular O-ring groove 61, an annular ball race 62, an annular ball release channel 63 and an annular tooling channel 64. A second counter bore 65 is provided in the mouth of the counter bore 60 to form a relatively thin sealing sleeve 66 which is an integral part of a female sleeve 67 formed by the counter bore 60.

A milling operation is performed on the metal located between the tooling channel 64 and the counter bore 65 to provide diametrically opposed axial passages 68 through said metal and circumferential passages (or right angle notches) 69 providing circumferential shoulders 7% disposed laterally from the passages 68. A threaded hole is bored through the wall of the female sleeve 67 within the confines of the annular race 62 for receiving a plug 76 for a purpose to be made clear hereinafter. The annular O-ring groove 61 is provided to receive an O- ring 77.

It is to be noted that the formation of the counter bore 66 in the coupling member 36 forms an annular internal shoulder 78 at the point of juncture between member 36 and female sleeve 67. The releasing coupling 28 also includes a large number of hardened ball bearing balls 79 and a release trigger assembly 8%) (PEG. 5). The latter unit includes a spider 81 including a metal band 82 having a multiplicity of arms 553, preferably four in number, on the outer end of each of which is mounted a metal block 84. The metal blocks $4 are supported on the spider 51 so that, prior to the assembly of the coupling 28, when the spider 81 is inserted in the female sleeve 67, the blocks 84 will rest on the shoulder 73 and will abut against the counter bore 60 so that the spider 81 is not readily displaced from this position. Furthermore the vertical dimension of the blocks 84 is such that when the male sleeve 59 is inserted downwardly in the female sleeve 67 so as to come to rest on the blocks 84, the ball races 53 and 62 are disposed opposite each other as shown in FIGS. 6 and 10. If, when the male sleeve is thus inserted into the female sleeve, the lugs 51 and 52 are located over the shoulders 7%, as shown in FIGS. 6 or 7, the lower end of the male sleeve is held a slight distance out of contact with the blocks 84. This relieves the latter of any pressure from the male sleeve as the weight of the male coupling member 35 is now supported by the lugs 51 and 52 resting on the shoulders 76.

The release trigger assembly 8%) also includes a molded rubber element 85 including a tubular core 945 which snugly fits within the metal band 82 and has an annular external shoulder 91 and a dished diaphragm 92. The tubular core has an axial hole 93 which may be made with various diameters for a purpose which will be explained later.

To assembly the releasing coupling 28, the release trigger assembly 3t) is inserted into the counter bore 6% to rest on the shoulder 73 as shown in FIG. 6 after which the O-rings 43 and 77 are inserted in their respective grooves 47 and 61 and the male sleeve 56 is inserted downwardly in the female sleeve 67 with the lugs 51 and 52 coming to rest on the shoulders 7% of the female sleeve. The screw plug 76 is now removed and the ball bearing balls 79 are inserted through hole 75 into the annular pocket provided by the juxtaposed ball races 53 and 62 and the plug 76 is then screwed in place to close the hole 75.

The releasing coupling 28 is now completely assembled and ready to be connected to adjoining sections of a well casing for performance of a cementing operation as above described.

OPERATION When the casing 25 is run into a well for an initial cementing operation as shown in FIG. 1 the various parts of the releasing coupling 28 are preferably positioned as shown in FIG. 6 so that the weight of the upper section 26 of the casing is imposed through the lugs 51 and 52 onto the shoulders '79 of the female member rather than being transmitted to said female member through the releasing blocks 8-4. Thus when a cement plug travelling down the casing 25 just following the charge 31 of liquid cement engages the diaphragm 92 of the release trigger assembly 30 as shown in FIG. 7, it closes the axial hole 93 and brings to bear upon the assembly 80 the entire hydraulic force of the descending column of liquid so as to collapse the spider 81 and pull the blocks 84 out from between the shoulder 78 and the the male sleeve 50. The assembly 80 is thus carried downward with the cement plug to the lower end of the casing section 27 where its engagement with the bull nose 30 causes a rise of pressure in the circulating liquid system at the top of the well showing that the cement charge 31 is in place and thus signalling for suspension of the operations until this charge is set sufficiently to perform the next cementing step illustrated in FIG. 2. When this time arrives the upper casing section 26 is rotated slightly in a clockwise direction to bring lugs 51 and 52 in alignment with the axial passages 68 in the inner surface of the female sleeve 67 so that when the upper casing section is now lowered it will cause the further penetration of the female sleeve 67 by the male sleeve 5%).

Immediately upon this taking place, as shown in FIG. 8, the ball bearing balls 79 gravitate downwardly into the ball release channel 63 so that when the drilling operator now lifts on the upper casing section 26 this pulls male releasing coupling member 35 free from the female coupling member 36, the separation of these two elements being shown taking place in FIG. 9.

It is to be noted that at any time during the cementing operation and before the separation of the respective tubular members 35 and 36 of the releasing coupling 23, torque may be transmitted from the upper casing section 26 to the lower casing section 27 through engagement of the rectangular lugs 51 and 52 with vertical faces of the passages 68 or 69.

The very high axial lifting capacity of the coupling 28 through the high shear resistance of the large number of bfls 79 employed in the coupling and the certainty and rapidity of the disengagement of these balls upon the actuation of the trigger assembly 80 are features of great merit in the present invention. Another great advantage is the certainty with which the trigger assembly is actuated upon engagement of a cement plug 95 therewith as shown in FIG. 7. The closing of the hole 93 by this plug brings into play the full pressure of the circulating liquid to immediately remove this trigger assembly from its position obstruction further penetration of the male member into the female member of the coupling.

Another advantageous feature is the adaptability of the coupling 28 with slight modifications of the molded rubber element 85 and the use of cement plugs varying in diameter so as to permit the introduction of two or more of these coupling in a single string of casing and the selective actuation of these couplings beginning with the lowermost coupling in the casing and progressing successively upwardly.

For instance, in a casing equipped with two releasing couplings 98 the hole 93 in the upper coupling would be substantially larger than the hole 93 in the lower coupling. Following the initial charge of cement 31 for the cementing operation shown in FIG. 1 would be a plug which would pass through the hole 93 in the upper coupling 23 but would close the hole 93 in the lower coupling 28, thereby collapsing the spider 81 of this and puslL'ng the trigger assembly 86 thereof downwardly, conditioning the lower coupling 28 for separation.

The second charge of cement 32 would now be followed by a plug which would close the hole 93 in the upper releasing coupling thus carrying away the trigger assembly thereof and conditioning that coupling for separation at the conclusion of the second cementing operation. This would permit a third cementing operation to be performed similar to the second cementing operation illustrated in FIG. 27

We claim:

1. In a releasable well casing coupling, the combination of: male and female interfitting tubular members; means on said members for securing the same to contiguous ends of adjoining sections of a well casing, the interfitting portions of said members comprising respectively telescopically related male and female sleeves; axially uni-directional locking means embodied with said sleeves and operative, with said male sleeve partially inserted into said female sleeve a given distance, to positively lock said male sl eve against withdrawal from said female sleeve, while permitting sm'd male sleeve to be inserted further into said female sleeve; means actuated by such further insertion of said male sleeve to render said locking means inoperative to prevent withdrawal of said male sleeve from said female sleeve; means positioned for temporarily blocking said further insertion of said male sleeve into said female sleeve, to maintain said locking means operative to lock said male sleeve against withdrawal from said f male sleeve; and means operable from the top of a well when said well casing is installed in said well for dislodging sm'd blocking means from said position to allow said male sleeve to further penetrate said female sleeve and thereby free said coupling members from connection by said locking means whereby said members may be readily separated axially.

2. A combination as recited in claim 1 wherein the means last recited extends inwardly into said coupling so as to be engaged by a plug introduced into liquid circulated downwardly through said casing whereby said means is actuated by said plug to dislodge said blocking means and thus facilitate the separation of said coupling members.

3. A combination as recited in claim 2 wherein said female member has an annular internal shoulder provided at its juncture with said female sleeve, and wherein said blocking means comprises a series of blocks interposed between said annular shoulder and said male sleeve, and said dislodging means comprises a diaphragm disposed within said coupling and connected to said blocks, said diaph agm having an axial hole therein which is smaller in diameter than said plug whereby engagement of said plug with said diaphragm closes said hole and imposes the full force of said circulating liquid on said diaphragm thereby dislodging said blocks from their positions aforesaid, thus facilitating the separaton of said coupling members.

4. A combination as recited in claim 1 wherein said locking means comprises annular primary and secondary ball races formed respectively in the slidably meeting cylindrical surfaces of said sleeves so as to be opposite each other when said male sleeve is partially inserted into said female sleeve as aforesaid, said primary ball race being provided in the sleeve of the coupling member which is disposed downwardly relative to the other coupling member, an annular ball release channel being formed in said last mentioned sleeve immediately below and in communication with the aforesaid primary ball race; and a series of ball bearing balls installed in said oppositely disposed races, said balls locking said coupling members together against axial separation so long as said locking means prevents further penetration of said female sleeve by said male sleeve, such further penetration, however, when accomplished, shifting said secondary ball race opposite said ball release channel which allows said balls to gravitate into said channel, the latter having a radial depth in excess of the diameter of said balls, whereby said balls no longer function to lock said members against axial separation.

5. A combination as recited in claim 4 wherein a plurality of rectangular lugs symmetrically distributed circumferentially are provided on said male sleeve near its juncture with said male member to extend radially beyond the aforesaid cylindrical surface of said sleeve; the mouth of said female sleeve being recessed to accommodate said lugs when said mme sleeve is inserted fully into said female sleeve, whereby rotationfl torque may be transmitted through said coupling.

6. A combination as recited in claim 5 wherein the recessing of said female sleeve provides axial passages for accommodating axial movement of said lugs relative to said female sleeve, and circumferential passages accommodating said lugs for limited relative rotation of said members when said male sleeve is only partially in serted into said female sleeve as aforesaid, radial shoulders on said female sleeve opposite said circumferential passages positively blocking further penetration of said female sleeve by said male sleeve, when said lugs are in said circumferential passages, and thus preventing the unlocking of said locking means, even after the functioning of said dislodging means, until said male sleeve is retated to return said lugs into said axial passages.

7. In a releasable coupling, the combination of: male and female interfitting tubular members, the interfitting portions of said members comprising respectively telescopically related male and female sleeves; uni-directional locking means embodied with said sleeves and operative, with said male sleeve partially inserted into said female sleeve a given distance, to positively lock said male sleeve against withdrawal from said female sleeve, while permitting said male sleeve to be inserted further into said female sleeve; means rendered efiective by such further insertion of said male sleeve to render said locking means inoperative to prevent withdrawal of said male sleeve from said female sleeve; means positioned for temporarily blocking said further insertion of said male sleeve into said female sleeve to maintain said locking means operative to lock said male sleeve against withdrawal from said female sleeve; and means located insidesaid coupling and operable from within said coupling for dislodglng said blocking means from said position to allow said male sleeve to further penetrate said female sleeve and thereby free said coupling members from connection by said locking means whereby said members may be readily separated axially.

References Cited in the file of this patent UNITED STATES PATENTS 1,033,187 Metzger July 23, 1912 2,518,443 Bagnard Aug. 15, 1950 2,860,893 Clark Nov. 18, 1958 

7. IN A RELEASABLE COUPLING, THE COMBINATION OF: MALE AND FEMALE INTERFITTING TUBULAR MEMBERS, THE INTERFITTING PORTIONS OF SAID MEMBERS COMPRISING RESPECTIVELY TELESCOPICALLY RELATED MALE AND FEMALE SLEEVES; UNI-DIRECTIONAL LOCKING MEANS EMBODIED WITH SAID SLEEVES AND OPERATIVE, WITH SAID MALE SLEEVE PARTIALLY INSERTED INTO SAID FEMALE SLEEVE A GIVEN DISTANCE, TO POSITIVELY LOCK SAID MALE SLEEVE AGAINST WITHDRAWAL FROM SAID FEMALE SLEEVE, WHILE PERMITTING SAID MALE SLEEVE TO BE INSERTED FURTHER INTO SAID FEMALE SLEEVE; MEANS RENDERED EFFECTIVE BY SUCH FURTHER INSERTION OF SAID MALE SLEEVE TO RENDER SAID LOCKING MEANS INOPERATIVE TO PREVENT WITHDRAWAL OF SAID MALE SLEEVE FROM SAID FEMALE SLEEVE; MEANS POSITIONED FOR TEMPORARILY BLOCKING SAID FURTHER INSERTION OF SAID MALE SLEEVE INTO SAID FEMALE SLEEVE TO MAINTAIN SAID LOCKING MEANS OPERATIVE TO LOCK SAID MALE SLEEVE AGAINST WITHDRAWAL FROM SAID FEMALE SLEEVE; AND MEANS LOCATED INSIDE SAID COUPLING AND OPERABLE FROM WITHIN SAID COUPLING 